Rabbi Meir Mazuz related in a recent Motz’ei Shabbos speech Rabbi Ratzon Arusi shlita (Rabbi Bar Ilan’s rabbi) encouraged the men in his city (Kiryat Ono, presumably) to wear their Tallis on the way to Shul. Why? Shabbos observance was suffering. He wished to publicize the Shabbos, and ensure it is honored. The custom stuck and spread.
That’s exactly what rabbis are for. And that’s exactly what customs are for.